Meaning : Allow to remain in a place or position or maintain a property or feature.
Example :
We cannot continue several servants any longer.
She retains a lawyer.
The family's fortune waned and they could not keep their household staff.
Our grant has run out and we cannot keep you on.
We kept the work going as long as we could.
She retained her composure.
This garment retains its shape even after many washings.
Keep on meaning in Bengali (Bangla).